1. Field of Invention
The invention pertains to coils, permanent magnet rotors, rotating and pivoting means for rotors of generators and motors, and means for accelerating the rotor or stator of these devices.
A dynamo-electric device has a brush-less, substantially iron-less stator of bobbin-type coil structure axially centered and surrounding the rotor, closely approximating the contour of the ellipsoid or spherical, permanent magnet rotor. The rotor includes a permanent magnet having at least one north and south pole face as sectors of the ellipsoid shape having stable and substantially uniform flux density across the entire surface area of the rotor. Such devices need not include a shaft, having means for suspending, supporting, and accelerating the rotor, including magnetic coupling to various external devices. In some embodiments the rotor is allowed multiple degrees of freedom with means for causing the rotor to rotate, reciprocate, or oscillate continuously or intermittently.
2. Description of Related Art
In many motors and generators the stator comprises a coil and the rotor comprises a permanent magnet. Usually coils are wound on stacks of laminated steel that faces the flux of the permanent magnet. Those skilled in the art are familiar with the associated problems of iron and heat losses, eddy currents, fringing flux, cogging, and noise.
Also, prior art shows examples of spherical motors. In U.S. Pat. No. 5,413,010 (Nakanishi et al.), a spherical electric motor is shown whereby a lattice-shaped array of magnets along a series of intersecting lines are embedded in a shell surface. In U.S. Pat. No. 3,178,600 (Bers), and in U.S. Pat. No. 5,204,570 (Gerfast), spherical motors are shown having spirally-wound, cup-shaped coils.
Other prior art shows motors that utilize a bobbin-type, or axial-centered coil. Over the years small, relatively compact motors and actuators have been used in cameras, from Uchiyama; 1973, to Matsumoto; 2002. Bobbin-type coils have been constructed to surround a permanent magnet rotor in the shape of a cylinder whereby a rotor has magnetic poles placed on a line extending in a magnetic direction. Such motors have been used to control shutter blades in cameras and various methods have been employed to connect operating members and linkages. In such devices, to accommodate the mechanics, the air gaps between the rotors and stator tend to be excessive and the entire surface areas of these shapes are not utilized.
Included in discussions of motors and the literature there is often a reminder that a motor can also be used as a generator or alternator. This is generally true if the shaft of a motor is turned fast enough. However, efficiency and output has no direct correlation in such uses. The dynamics and physical geometries of magnetic flux in an “active” state and a “passive” state produce different results and are based on entirely different phenomena. An energized coil in the case of a motor having a driving current will produce a magnetic field which may then be used to torque a rotor. In the “passive” state as represented by a generator, magnetic flux must sweep by a non-energized coil structure to induce a current. The laws of induction apply in contrast to the methods for producing torque in permanent magnet motors whereby two magnetic fields are caused to react with one another.
Regarding induction, it is known that moving a magnetic pole face and associated flux across a conductor at a ninety degree angle induces current to flow through the conductor; and alternately, by moving a magnet passed a coil a flux differential causes current to flow in a circuit. Usually, iron cores are added to the coils because the geometries of most generators are not able to place coils effectively in the path of rotating flux. Without the iron cores, most of the flux would bend around the coils instead of passing through them since magnetic flux will seek a path of least resistance. The addition of iron to the coils is to capture and direct the magnetic field lines in a linear direction as the rotor spins passed the coils; and so, such construction can be viewed as a series of linear alternators having coils that extend increasingly at a distance from the source of flux and magnetic flux that additionally decreases in density with distance. This is why linear alternators are mostly inefficient. Also, additional torque is required to move the magnet beyond its natural attraction to the iron.
Prior art coils that do not use the addition of iron cores suffer by geometry the previously stated rule of induction. Magnetic flux must cross a conductor at an optimal ninety degree angle to efficiently induce current and only those sections of a coil so disposed will produce significant current. Those large areas of a coil that are aligned with the direction of moving flux field lines produce no current and only serve as conductors to continue the circuit. For these reasons the shape and placement of a coil, the shape and placement of magnetic flux, and the relative movement between the two become important factors in generator output.
As electronic and power consuming devices become smaller, there arises the need for compact, high-output devices for charging and driving them by way of efficient energy conversion. Much time and study has been spent analyzing various methods for harvesting the energy of everyday human motion and using it to power mobile devices. Also, a few alternative powered products have been developed. Summaries and conclusions in the prior art, however, have expressed the shortcomings that are present. For example, work that has been done to provide a generator in the sole of a shoe has involved attempts at utilizing a small gear box to accelerate at the necessary speed a small dc motor as a generator. Outputs of such have been minimal and the friction and wear characteristics of the various mechanical elements are of major concern. Other attempts have utilized piezo, linear coils, and electrostrictive polymers. These have yielded even less results. A suitable generator for micro-scale devices has not been achieved and the various studies and attempts have left open a call for more improvements. A robust, modular generator capable of efficient motion and energy conversion can solve these and other issues including transcutaneous power transmission, motion conversion in marine or hermetic environments, etc. Large-scale devices are also possible. Needs exist for military and space applications as well as industrial and consumer markets.